// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
 * Ceph - scalable distributed file system
 *
 * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software 
 * Foundation.  See file COPYING.
 * 
 */

#ifndef CEPH_DISTRIBUTION_H
#define CEPH_DISTRIBUTION_H

#include <vector>

class Distribution
{
    vector<float> p;
    vector<int> v;

public:
    //Distribution() {
    //}

    unsigned get_width()
    {
        return p.size();
    }

    void clear()
    {
        p.clear();
        v.clear();
    }
    void add(int val, float pr)
    {
        p.push_back(pr);
        v.push_back(val);
    }

    void random()
    {
        float sum = 0.0;
        for (unsigned i = 0; i < p.size(); i++)
        {
            p[i] = (float)(rand() % 10000);
            sum += p[i];
        }
        for (unsigned i = 0; i < p.size(); i++)
            p[i] /= sum;
    }

    int sample()
    {
        float s = (float)(rand() % 10000) / 10000.0;
        for (unsigned i = 0; i < p.size(); i++)
        {
            if (s < p[i])
                return v[i];
            s -= p[i];
        }
        ceph_abort();
        return v[p.size() - 1]; // hmm.  :/
    }

    float normalize()
    {
        float s = 0.0;
        for (unsigned i = 0; i < p.size(); i++)
            s += p[i];
        for (unsigned i = 0; i < p.size(); i++)
            p[i] /= s;
        return s;
    }
};

#endif
